Safety helmets are made in a variety of configurations, however, at least the majority of helmet designs include a stiff, inflexible outer shell and some type of interior cushioning. More advanced helmet designs incorporate some type of energy absorbing system or material at limited locations within the hard outer shell.
The stiff shell of conventional safety helmets is designed to resist blows and to remain intact thereunder so that the forces of blows are distributed over those areas of the wearer's head engaging the interior of the helmet and to this end helmet shells are commonly formed of Fiberglas or the like. Any practically dimensioned and constructed helmet shell does, however, have some upper limit of shock resistance and will physically break upon impact exceeding this upper limit. Unfortunately any helmet impact so great as to break the helmet shell allows the force of the impact to be applied to a small skull area of the user, usually with disastrous results.
The inflexible nature of conventional helmets makes the wearing thereof relatively uncomfortable. Although helmets are provided in different "hat" sizes, the helmet interior only engages the head of a wearer in a limited number of locations and is far from form fitting. This is also disadvantageous in limiting the area of a skull that must bear the force of a blow administered to the helmet thereabout so that the forces applied to the skull are concentrated on these areas.